Removing header buttons

Hi,
Thank you for the amazing theme.
I want to remove the two button on the header and the header text down a bit.
I have added the following css to the custom css.
However, it only work fine on the website view, but not on tablet or mobile devices.

.header-button {
display: none;
}

.header-text {
width: 100%;
position: absolute;
}
.header-text {
top: 60px;
}

it will be greatly appreciated if you can help me out here.
thank you!